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Check engine light after exhaust manifold replacement

walkerc

NAXJA Forum User
Location
Atlanta
1995 Cherokee Country Auto, 150k miles

Got my exhaust manifold replaced yesterday by a mechanic. Car had no CEL prior. With the new manifold on I have a CEL and a rough idle. I picked it up from his house and he had no scan tool to check the light... took it down to auto zone but they couldn't read it either. My thinking is maybe he messed up the firing order.. help would be appreciated.
 
X2 on the o2 sensor. Made that mistake myself on one of my many exhaust manifold swaps. Didn't get the running like crap part though as mine was sitting idle burning the oil off new manifold when I saw the light come on.

I guess the only way for the firing order to be messed up would be if he plugged the injectors back up wrong. There's only 2 or 3 that I recall that can be easily plugged up wrong, and I beileve they're the 2-3 in the middle of the rail.
 
Not to sound like a douche, but what kind of mechanic doesn't have a scan tool?

Where in Atlanta are you? I just bought a laptop scan tool a couple weeks ago, and it works fine for my XJ. If you're nearby I'll be happy to scan it for you.
 
I am not a great mechanic and newb myself but in spirit of giving back to community and helping others. There could be a debris that fell into the exhaust when it was replaced, so it's possible it screw up your O2 Sensor, that's if it is connected at all.
The connector to O2 sensor should be located on one of the oil pan studs and it's at the end of the harness that goes onto the injectors.
Try resetting the CEL, it may not come ON again.
 
double check the injector wires are fully clicked together, i replaced injector 0-rings and didn't push one clip in far enough and got your result
 
I wasn't in Atlanta at the time, South Carolina. I ended up driving all around town to all the shops and no one had a snap on. I stopped in at West Wateree Off Road and they recommended I head down the street to a shop that had a Snap on. Hooked it up and told me the upstream O2 sensor wires had shorted.

Short on time I had to drive all the way to Atl with a bad O2. I cringed the whole way looking at the gas gauge. I have a new Bosch O2 on now and everything is fine. Now there's an exhaust leak where the down pipe meets the exhaust manifold. Getting that fixed as soon as my new down pipe and gasket get here.
 
I wasn't in Atlanta at the time, South Carolina. I ended up driving all around town to all the shops and no one had a snap on. I stopped in at West Wateree Off Road and they recommended I head down the street to a shop that had a Snap on. Hooked it up and told me the upstream O2 sensor wires had shorted.

Short on time I had to drive all the way to Atl with a bad O2. I cringed the whole way looking at the gas gauge. I have a new Bosch O2 on now and everything is fine. Now there's an exhaust leak where the down pipe meets the exhaust manifold. Getting that fixed as soon as my new down pipe and gasket get here.

Good, glad you got it sorted. Basically the same thing that happened to me.
 
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